Rock Mining The Oldest Profession

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Published: Monday, 16 August 2010 12:10

Written by Rock Products News

For those having a difficult time making the case with political and community leaders that aggregate mining and processing aids the economy, here's another tact—it maybe the oldest profession and one that helped early humans prosper

For those having a difficult time making the case with political and community leaders that aggregate mining and processing aids the economy, here's another tactóit maybe the oldest profession and one that helped early humans prosper.

Two Arizona State University researchers conducting zooarchaeological and archaeometric analyses of four fossilized animal bone fragments found by the Dikika Research Project in northeastern Ethiopia--within walking distance of the discovery of the hominin skeleton Lucy (A. afarensis)--confirm that unusual marks on the bones were inflicted by stone tools. Their conclusion weighs in on findings that A. afarensis used sharp-edged stones and a strong striking force to cleave flesh and marrow from large-sized animal carcasses some 3.4 million years ago.

That evidence pushes back the origins of technology--the use of stone tools--and carnivory by some 800,000 years, said Curtis Marean, a paleoanthropologist at ASUís Institute of Human Origins and one of the worldís leading experts in the study of animal bones from archaeological sites.

Marean, a professor in the School of Human Evolution and Social Change in ASUís College of Liberal Arts and Sciences, is a member of the international team made up of experts in paleoanthropology, archeology, geology, paleontology and materials science who reported the findings in the Nature article, ìEvidence for stone-tool-assisted consumption of animal tissues before 3.39 million years ago at Dikika, Ethiopia.î

Zooarchaeological analysis of the bone fragments, which included a femur shaft from an animal the size of a goat and a rib fragment from a much larger animal the size of a cow, was conducted at Arizona State University. Using a standard binocular microscope in ASUís zooarchaeology laboratory, Marean was able to provide evidence that sharp-edged stones and a strong striking force were used to remove flesh and marrow from the bones of large-sized animal carcasses. To further determine that the markings were not modern, he turned to Hamdallah BÈarat, a senior research scientist at ASUís School for Engineering of Matter, Transport and Energy.

ìTo confirm that the cut marks on the bones are old and verify that they were induced by stone tools, I used the Environmental Cell Scanning Electron Microscope (E-SEM) and the attached Energy Dispersive X-ray Spectrometry (EDX) in ASUís LeRoy Eyring Center for Solid State Science,î said BÈarat, who has degrees in chemistry, archaeometry, material science and engineering.

The E-SEM was used because it has a chamber and stage that can accommodate large bone fragments, BÈarat explained. ìAnd, since the bone material is an insulator and these precious bone samples cannot be coated with a conducting film, such as gold or carbon, this E-SEM allows us to run the analysis in the H2O-vapor mode and thus avoid charging effects, while still using a high accelerating voltage (15-25kV),î BÈarat said.

ìHamdallah is an expert in materials research and keenly interested in archaeology,î said Marean. ìHe had the great idea to do X-ray mapping of the surfaces of the bone to see whether minerals that passed from the marks to the surface of the bone were fossilized.î The geologist on the team, Jonathan Wynn, from the University of South Florida, relied on documented dated volcanic deposits in the Dikika area to estimate the date of the marked bones to 3.4 million years ago.

ìThis discovery dramatically shifts the known time frame of a game-changing behavior for our ancestors,î said paleoanthropologist Zeresenay Alemseged, director of the Dikika project and director of anthropology at the California Academy of Sciences.

No hominin remains were found with the animal bone fragments that were uncovered 200 meters away from the site where Alemseged and a team discovered Selam (Lucyís baby) in 2000. Lucy was discovered in 1974 a few miles north, near Hadar, by Donald Johanson, an ASU paleoanthropologist.

ìThere is no question that the announcement of stone tool use at 3.4 million years ago will unleash a flurry of controversy and genuine disbelief among some scholars,î said Johanson. ìHowever, I believe the team has presented a convincing case of stone tool use during Lucyís time. These unexpected results may well generate a new understanding of early hominid behavior and will prompt a reexamination of the tens of thousands of animal bones already collected from this time period at Hadar, Lucyís home, and other sites in Kenya and Tanzania.

ìVery often it is breakthroughs such as this that stimulate new and expanded research strategies that promise to significantly enlarge our understanding of human origins,î Johanson said.

Lead author of the Nature article Shannon McPherron said, ìNow, when we imagine Lucy walking around the east African landscape looking for food, we can for the first time imagine her doing so with a stone tool in her hand.î McPherron is an archeologist with the Dikika project and research scientist at the Max Planck Institute in Leipzig, Germany. He and Alemseged led the Dikika fieldwork.

The last place early humans--like Lucy--wanted to be on the African landscape was in a competitive dangerous situation next to an animal carcass, said Marean.

Yet, ìthese marks are unusual compared to other butchery marks I have seen,î he said. ìThey show a lot of force, a lot of heavy action.î

Marean framed the research findings as ìa spectacular and exciting discovery pertaining to early human evolution.î But, while the evidence shows the Australopithecines at Dikika were using sharp-edged stones to crack and strip meat from the bones, it is impossible to tell from the marks alone whether these early hominins were making their tools and carrying them, or simply finding naturally sharp rocks.

Many questions remain about the use of stone tools by human ancestors and the introduction of meat into their diet. ìThe subtle implication is that in this instance, it was not hunted but scavenged meat and marrow, since the really large animal was almost certainly outside the ability of hominins to kill. This could be a key tipping point in the origins of human uniqueness,î Marean said. ìOne of the big steps in human evolution is when males and females pair-bond, and males provided females with meat. This result may suggest this is happening at this early stage in human origins.î